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<H1 class="no-header">curs_attr 3x 2024-04-27 ncurses 6.5 Library calls</H1>
<PRE>
<STRONG><A HREF="curs_attr.3x.html">curs_attr(3x)</A></STRONG>                    Library calls                   <STRONG><A HREF="curs_attr.3x.html">curs_attr(3x)</A></STRONG>




</PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
       <STRONG>attr_get</STRONG>, <STRONG>wattr_get</STRONG>, <STRONG>attr_set</STRONG>, <STRONG>wattr_set</STRONG>, <STRONG>attr_off</STRONG>, <STRONG>wattr_off</STRONG>, <STRONG>attr_on</STRONG>,
       <STRONG>wattr_on</STRONG>, <STRONG>attroff</STRONG>, <STRONG>wattroff</STRONG>, <STRONG>attron</STRONG>, <STRONG>wattron</STRONG>, <STRONG>attrset</STRONG>, <STRONG>wattrset</STRONG>, <STRONG>chgat</STRONG>,
       <STRONG>wchgat</STRONG>,  <STRONG>mvchgat</STRONG>, <STRONG>mvwchgat</STRONG>, <STRONG>color_set</STRONG>, <STRONG>wcolor_set</STRONG>, <STRONG>standend</STRONG>, <STRONG>wstandend</STRONG>,
       <STRONG>standout</STRONG>, <STRONG>wstandout</STRONG> -  manipulate  attributes  of  character  cells  in
       <EM>curses</EM> windows


</PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
       <STRONG>#include</STRONG> <STRONG>&lt;curses.h&gt;</STRONG>

       <STRONG>int</STRONG> <STRONG>attr_get(attr_t</STRONG> <STRONG>*</STRONG><EM>attrs</EM><STRONG>,</STRONG> <STRONG>short</STRONG> <STRONG>*</STRONG><EM>pair</EM><STRONG>,</STRONG> <STRONG>void</STRONG> <STRONG>*</STRONG><EM>opts</EM><STRONG>);</STRONG>
       <STRONG>int</STRONG> <STRONG>wattr_get(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>attr_t</STRONG> <STRONG>*</STRONG><EM>attrs</EM><STRONG>,</STRONG> <STRONG>short</STRONG> <STRONG>*</STRONG><EM>pair</EM><STRONG>,</STRONG> <STRONG>void</STRONG> <STRONG>*</STRONG><EM>opts</EM><STRONG>);</STRONG>
       <STRONG>int</STRONG> <STRONG>attr_set(attr_t</STRONG> <EM>attrs</EM><STRONG>,</STRONG> <STRONG>short</STRONG> <EM>pair</EM><STRONG>,</STRONG> <STRONG>void</STRONG> <STRONG>*</STRONG><EM>opts</EM><STRONG>);</STRONG>
       <STRONG>int</STRONG> <STRONG>wattr_set(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>attr_t</STRONG> <EM>attrs</EM><STRONG>,</STRONG> <STRONG>short</STRONG> <EM>pair</EM><STRONG>,</STRONG> <STRONG>void</STRONG> <STRONG>*</STRONG><EM>opts</EM><STRONG>);</STRONG>

       <STRONG>int</STRONG> <STRONG>attr_off(attr_t</STRONG> <EM>attrs</EM><STRONG>,</STRONG> <STRONG>void</STRONG> <STRONG>*</STRONG><EM>opts</EM><STRONG>);</STRONG>
       <STRONG>int</STRONG> <STRONG>wattr_off(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>attr_t</STRONG> <EM>attrs</EM><STRONG>,</STRONG> <STRONG>void</STRONG> <STRONG>*</STRONG><EM>opts</EM><STRONG>);</STRONG>
       <STRONG>int</STRONG> <STRONG>attr_on(attr_t</STRONG> <EM>attrs</EM><STRONG>,</STRONG> <STRONG>void</STRONG> <STRONG>*</STRONG><EM>opts</EM><STRONG>);</STRONG>
       <STRONG>int</STRONG> <STRONG>wattr_on(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>attr_t</STRONG> <EM>attrs</EM><STRONG>,</STRONG> <STRONG>void</STRONG> <STRONG>*</STRONG><EM>opts</EM><STRONG>);</STRONG>

       <STRONG>int</STRONG> <STRONG>attroff(int</STRONG> <EM>attrs</EM><STRONG>);</STRONG>
       <STRONG>int</STRONG> <STRONG>wattroff(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>attrs</EM><STRONG>);</STRONG>
       <STRONG>int</STRONG> <STRONG>attron(int</STRONG> <EM>attrs</EM><STRONG>);</STRONG>
       <STRONG>int</STRONG> <STRONG>wattron(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>attrs</EM><STRONG>);</STRONG>
       <STRONG>int</STRONG> <STRONG>attrset(int</STRONG> <EM>attrs</EM><STRONG>);</STRONG>
       <STRONG>int</STRONG> <STRONG>wattrset(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>attrs</EM><STRONG>);</STRONG>

       <STRONG>int</STRONG> <STRONG>chgat(int</STRONG> <EM>n</EM><STRONG>,</STRONG> <STRONG>attr_t</STRONG> <EM>attr</EM><STRONG>,</STRONG> <STRONG>short</STRONG> <EM>pair</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>void</STRONG> <STRONG>*</STRONG><EM>opts</EM><STRONG>);</STRONG>
       <STRONG>int</STRONG> <STRONG>wchgat(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG>
             <STRONG>int</STRONG> <EM>n</EM><STRONG>,</STRONG> <STRONG>attr_t</STRONG> <EM>attr</EM><STRONG>,</STRONG> <STRONG>short</STRONG> <EM>pair</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>void</STRONG> <STRONG>*</STRONG><EM>opts</EM><STRONG>);</STRONG>
       <STRONG>int</STRONG> <STRONG>mvchgat(int</STRONG> <EM>y</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>x</EM><STRONG>,</STRONG>
             <STRONG>int</STRONG> <EM>n</EM><STRONG>,</STRONG> <STRONG>attr_t</STRONG> <EM>attr</EM><STRONG>,</STRONG> <STRONG>short</STRONG> <EM>pair</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>void</STRONG> <STRONG>*</STRONG><EM>opts</EM><STRONG>);</STRONG>
       <STRONG>int</STRONG> <STRONG>mvwchgat(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>y</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>x</EM><STRONG>,</STRONG>
             <STRONG>int</STRONG> <EM>n</EM><STRONG>,</STRONG> <STRONG>attr_t</STRONG> <EM>attr</EM><STRONG>,</STRONG> <STRONG>short</STRONG> <EM>pair</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>void</STRONG> <STRONG>*</STRONG><EM>opts</EM><STRONG>);</STRONG>

       <STRONG>int</STRONG> <STRONG>color_set(short</STRONG> <EM>pair</EM><STRONG>,</STRONG> <STRONG>void*</STRONG> <EM>opts</EM><STRONG>);</STRONG>
       <STRONG>int</STRONG> <STRONG>wcolor_set(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>short</STRONG> <EM>pair</EM><STRONG>,</STRONG> <STRONG>void*</STRONG> <EM>opts</EM><STRONG>);</STRONG>

       <STRONG>int</STRONG> <STRONG>standend(void);</STRONG>
       <STRONG>int</STRONG> <STRONG>wstandend(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>);</STRONG>
       <STRONG>int</STRONG> <STRONG>standout(void);</STRONG>
       <STRONG>int</STRONG> <STRONG>wstandout(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>);</STRONG>


</PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
       These  routines  manipulate the current attributes of the named window,
       which then apply to all characters that are  written  into  the  window
       with  <STRONG>waddch</STRONG>,  <STRONG>waddstr</STRONG>  and  <STRONG>wprintw</STRONG>.  Attributes are a property of the
       character, and move  with  the  character  through  any  scrolling  and
       insert/delete  line/character operations.  To the extent possible, they
       are displayed as appropriate modifications to the graphic rendition  of
       characters put on the screen.

       These  routines do not affect the attributes used when erasing portions
       of the window.   See  <STRONG><A HREF="curs_bkgd.3x.html">curs_bkgd(3x)</A></STRONG>  for  functions  which  modify  the
       attributes used for erasing and clearing.


</PRE><H3><a name="h3-Window-Attributes">Window Attributes</a></H3><PRE>
       There are two sets of functions:

       <STRONG>o</STRONG>   functions   for  manipulating  the  window  attributes  and  color:
           <STRONG>wattr_set</STRONG> and <STRONG>wattr_get</STRONG>.

       <STRONG>o</STRONG>   functions for manipulating only the window attributes (not  color):
           <STRONG>wattr_on</STRONG> and <STRONG>wattr_off</STRONG>.

       The  <STRONG>wattr_set</STRONG> function sets the current attributes of the given window
       to <EM>attrs</EM>, with color specified by <EM>pair</EM>.

       Use <STRONG>wattr_get</STRONG> to retrieve attributes for the given window.

       Use <STRONG>attr_on</STRONG> and <STRONG>wattr_on</STRONG> to turn on  window  attributes,  i.e.,  values
       OR'd  together  in  <EM>attr</EM>,  without  affecting  other  attributes.   Use
       <STRONG>attr_off</STRONG> and <STRONG>wattr_off</STRONG> to turn off window attributes, again values OR'd
       together in <EM>attr</EM>, without affecting other attributes.


</PRE><H3><a name="h3-Legacy-Window-Attributes">Legacy Window Attributes</a></H3><PRE>
       The  X/Open  window attribute routines which <EM>set</EM> or <EM>get</EM>, turn <EM>on</EM> or <EM>off</EM>
       are extensions of older routines which assume that color pairs are OR'd
       into  the attribute parameter.  These newer routines use similar names,
       because X/Open simply added an underscore (<STRONG>_</STRONG>) for the newer names.

       The <STRONG>int</STRONG> datatype used in the legacy routines is treated as if it is the
       same  size  as  <STRONG>chtype</STRONG>  (used by <STRONG><A HREF="curs_addch.3x.html">addch(3x)</A></STRONG>).  It holds the common video
       attributes (such as bold, reverse), as well as a few  bits  for  color.
       Those  bits  correspond  to  the  <STRONG>A_COLOR</STRONG> symbol.  The <STRONG>COLOR_PAIR</STRONG> macro
       provides a value which can be OR'd into the attribute  parameter.   For
       example,  as  long as that value fits into the <STRONG>A_COLOR</STRONG> mask, then these
       calls produce similar results:

           attrset(A_BOLD | COLOR_PAIR(<EM>pair</EM>));
           attr_set(A_BOLD, <EM>pair</EM>, NULL);

       However, if the value does not fit, then the <STRONG>COLOR_PAIR</STRONG> macro uses only
       the  bits  that fit.  For example, because in <EM>ncurses</EM> <STRONG>A_COLOR</STRONG> has eight
       (8) bits, then <STRONG>COLOR_PAIR(</STRONG><EM>259</EM><STRONG>)</STRONG> is 4 (i.e., 259 is 4 more than the limit
       255).

       The  <STRONG>PAIR_NUMBER</STRONG>  macro extracts a pair number from an <STRONG>int</STRONG> (or <STRONG>chtype</STRONG>).
       For example, the <EM>input</EM> and <EM>output</EM> values in these statements  would  be
       the same:

           int value = A_BOLD | COLOR_PAIR(<EM>input</EM>);
           int <EM>output</EM> = PAIR_NUMBER(value);

       The  <STRONG>attrset</STRONG> routine is a legacy feature predating SVr4 curses but kept
       in X/Open Curses  for  the  same  reason  that  SVr4  curses  kept  it:
       compatibility.

       The  remaining  <STRONG>attr</STRONG>*  functions operate exactly like the corresponding
       <STRONG>attr_</STRONG>* functions, except that they take arguments of  type  <STRONG>int</STRONG>  rather
       than <STRONG>attr_t</STRONG>.

       There  is  no  corresponding <STRONG>attrget</STRONG> function as such in X/Open Curses,
       although <EM>ncurses</EM> provides <STRONG>getattrs</STRONG> (see <STRONG><A HREF="curs_legacy.3x.html">curs_legacy(3x)</A></STRONG>).


</PRE><H3><a name="h3-Change-Character-Rendition">Change Character Rendition</a></H3><PRE>
       The  routine  <STRONG>chgat</STRONG>  changes  the  attributes  of  a  given  number  of
       characters  starting at the current cursor location of <STRONG>stdscr</STRONG>.  It does
       not update the cursor and does not perform wrapping.  A character count
       of  -1  or  greater  than  the  remaining  window width means to change
       attributes all the way to the end of  the  current  line.   The  <STRONG>wchgat</STRONG>
       function  generalizes  this to any window; the <STRONG>mvwchgat</STRONG> function does a
       cursor move before acting.

       In these functions, the color <EM>pair</EM> argument is a color pair  index  (as
       in the first argument of <STRONG>init_pair</STRONG>, see <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG>).


</PRE><H3><a name="h3-Change-Window-Color">Change Window Color</a></H3><PRE>
       The routine <STRONG>color_set</STRONG> sets the current color of the given window to the
       foreground/background  combination  described   by   the   color   <EM>pair</EM>
       parameter.


</PRE><H3><a name="h3-Standout">Standout</a></H3><PRE>
       The  routine  <STRONG>standout</STRONG>  is the same as <STRONG>attron(A_STANDOUT)</STRONG>.  The routine
       <STRONG>standend</STRONG> is the same as <STRONG>attrset(A_NORMAL)</STRONG> or <STRONG>attrset(0)</STRONG>,  that  is,  it
       turns off all attributes.

       X/Open Curses does not mark these "restricted", because

       <STRONG>o</STRONG>   they have well established legacy use, and

       <STRONG>o</STRONG>   there  is  no  ambiguity  about  the  way  the  attributes might be
           combined with a color pair.


</PRE><H3><a name="h3-Video-Attributes">Video Attributes</a></H3><PRE>
       The following video attributes, defined in <STRONG>&lt;curses.h&gt;</STRONG>, can be passed to
       the  routines <STRONG>attron</STRONG>, <STRONG>attroff</STRONG>, and <STRONG>attrset</STRONG>, or OR'd with the characters
       passed to <STRONG>addch</STRONG> (see <STRONG><A HREF="curs_addch.3x.html">curs_addch(3x)</A></STRONG>).

              <STRONG>Name</STRONG>           <STRONG>Description</STRONG>
              -----------------------------------------------------------------
              <STRONG>A_NORMAL</STRONG>       Normal display (no highlight)
              <STRONG>A_STANDOUT</STRONG>     Best highlighting mode of the terminal
              <STRONG>A_UNDERLINE</STRONG>    Underlining
              <STRONG>A_REVERSE</STRONG>      Reverse video
              <STRONG>A_BLINK</STRONG>        Blinking
              <STRONG>A_DIM</STRONG>          Half bright
              <STRONG>A_BOLD</STRONG>         Extra bright or bold
              <STRONG>A_PROTECT</STRONG>      Protected mode
              <STRONG>A_INVIS</STRONG>        Invisible or blank mode
              <STRONG>A_ALTCHARSET</STRONG>   Alternate character set
              <STRONG>A_ITALIC</STRONG>       Italics (non-X/Open extension)
              <STRONG>A_CHARTEXT</STRONG>     Bit-mask to extract a character
              <STRONG>A_COLOR</STRONG>        Bit-mask to extract a color (legacy routines)

       These video attributes are supported by <STRONG>attr_on</STRONG> and  related  functions
       (which also support the attributes recognized by <STRONG>attron</STRONG>, etc.):

              <STRONG>Name</STRONG>            <STRONG>Description</STRONG>
              -----------------------------------------------------------------
              <STRONG>WA_HORIZONTAL</STRONG>   Horizontal highlight
              <STRONG>WA_LEFT</STRONG>         Left highlight
              <STRONG>WA_LOW</STRONG>          Low highlight
              <STRONG>WA_RIGHT</STRONG>        Right highlight
              <STRONG>WA_TOP</STRONG>          Top highlight
              <STRONG>WA_VERTICAL</STRONG>     Vertical highlight

       The  return  values  of many of these routines are not meaningful (they
       are implemented as macro-expanded assignments and simply  return  their
       argument).   The  SVr4 manual page claims (falsely) that these routines
       always return <STRONG>1</STRONG>.


</PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
       All routines return the integer <STRONG>OK</STRONG> on success, or <STRONG>ERR</STRONG> on failure.

       X/Open Curses does not specify any error conditions.

       This implementation

       <STRONG>o</STRONG>   returns an error if the window pointer is null.

       <STRONG>o</STRONG>   returns an error if the color  pair  parameter  for  <STRONG>wcolor_set</STRONG>  is
           outside the range 0..COLOR_PAIRS-1.

       <STRONG>o</STRONG>   does  not  return an error if either of the parameters of <STRONG>wattr_get</STRONG>
           used for retrieving attribute or color pair values is <STRONG>NULL</STRONG>.

       Functions prefixed with "mv" first perform cursor movement and fail  if
       the position (<EM>y</EM>, <EM>x</EM>) is outside the window boundaries.


</PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
       These functions may be macros:

              <STRONG>attroff</STRONG>,  <STRONG>wattroff</STRONG>, <STRONG>attron</STRONG>, <STRONG>wattron</STRONG>, <STRONG>attrset</STRONG>, <STRONG>wattrset</STRONG>, <STRONG>standend</STRONG>
              and <STRONG>standout</STRONG>.

       Color pair values can only be OR'd with attributes if the  pair  number
       is less than 256.  The alternate functions such as <STRONG>color_set</STRONG> can pass a
       color pair value directly.  However, <EM>ncurses</EM> ABI 4 and 5 simply OR this
       value  within  the  alternate functions.  You must use <EM>ncurses</EM> ABI 6 to
       support more than 256 color pairs.


</PRE><H2><a name="h2-EXTENSIONS">EXTENSIONS</a></H2><PRE>
       This implementation provides the <STRONG>A_ITALIC</STRONG> attribute for terminals which
       have   the   <STRONG>enter_italics_mode</STRONG>  (<STRONG>sitm</STRONG>)  and  <STRONG>exit_italics_mode</STRONG>  (<STRONG>ritm</STRONG>)
       capabilities.  Italics are not mentioned in X/Open Curses.  Unlike  the
       other  video  attributes,  <STRONG>A_ITALIC</STRONG>  is unrelated to the <STRONG>set_attributes</STRONG>
       capabilities.   This   implementation   makes   the   assumption   that
       <STRONG>exit_attribute_mode</STRONG> may also reset italics.

       Each  of  the functions added by XSI Curses has a parameter <EM>opts</EM>, which
       X/Open Curses  still  (after  more  than  twenty  years)  documents  as
       reserved  for  future  use,  saying  that  it  should  be  <STRONG>NULL</STRONG>.   This
       implementation uses that parameter in ABI 6  for  the  functions  which
       have a color pair parameter to support <EM>extended</EM> <EM>color</EM> <EM>pairs</EM>:

       <STRONG>o</STRONG>   For functions which modify the color, e.g., <STRONG>wattr_set</STRONG> and <STRONG>wattr_on</STRONG>,
           if <EM>opts</EM> is set it is treated as a pointer to <STRONG>int</STRONG>, and used  to  set
           the color pair instead of the <STRONG>short</STRONG> <EM>pair</EM> parameter.

       <STRONG>o</STRONG>   For functions which retrieve the color, e.g., <STRONG>wattr_get</STRONG>, if <EM>opts</EM> is
           set it is treated as a pointer to <STRONG>int</STRONG>, and  used  to  retrieve  the
           color  pair  as  an <STRONG>int</STRONG> value, in addition to retrieving it via the
           standard pointer to <STRONG>short</STRONG> parameter.

       <STRONG>o</STRONG>   For functions which turn attributes off, e.g., <STRONG>wattr_off</STRONG>, the  <EM>opts</EM>
           parameter is ignored except except to check that it is <STRONG>NULL</STRONG>.


</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
       These  functions are described in X/Open Curses, Issue 4.  The standard
       defined the dedicated  type  for  highlights,  <STRONG>attr_t</STRONG>,  which  was  not
       defined in SVr4 curses.  The functions taking <STRONG>attr_t</STRONG> arguments were not
       supported under SVr4.

       Very old versions of this library did not force an update of the screen
       when  changing  the  attributes.   Use  <STRONG>touchwin</STRONG> to force the screen to
       match the updated attributes.

       X/Open  Curses  states   that   whether   the   traditional   functions
       <STRONG>attron</STRONG>/<STRONG>attroff</STRONG>/<STRONG>attrset</STRONG>  can  manipulate  attributes other than <STRONG>A_BLINK</STRONG>,
       <STRONG>A_BOLD</STRONG>, <STRONG>A_DIM</STRONG>, <STRONG>A_REVERSE</STRONG>, <STRONG>A_STANDOUT</STRONG>, or <STRONG>A_UNDERLINE</STRONG> is  "unspecified".
       Under  this  implementation  as  well  as  SVr4 curses, these functions
       correctly manipulate all other highlights (specifically,  <STRONG>A_ALTCHARSET</STRONG>,
       <STRONG>A_PROTECT</STRONG>, and <STRONG>A_INVIS</STRONG>).

       X/Open Curses added these entry points:

              <STRONG>attr_get</STRONG>,  <STRONG>attr_on</STRONG>,  <STRONG>attr_off</STRONG>,  <STRONG>attr_set</STRONG>,  <STRONG>wattr_on</STRONG>,  <STRONG>wattr_off</STRONG>,
              <STRONG>wattr_get</STRONG>, <STRONG>wattr_set</STRONG>

       The new functions are intended to work with a new series  of  highlight
       macros prefixed with <STRONG>WA_</STRONG>.  The older macros have direct counterparts in
       the newer set of names:

              <STRONG>Name</STRONG>            <STRONG>Description</STRONG>
              -----------------------------------------------------------------
              <STRONG>WA_NORMAL</STRONG>       Normal display (no highlight)
              <STRONG>WA_STANDOUT</STRONG>     Best highlighting mode of the terminal
              <STRONG>WA_UNDERLINE</STRONG>    Underlining
              <STRONG>WA_REVERSE</STRONG>      Reverse video
              <STRONG>WA_BLINK</STRONG>        Blinking
              <STRONG>WA_DIM</STRONG>          Half bright
              <STRONG>WA_BOLD</STRONG>         Extra bright or bold

              <STRONG>WA_ALTCHARSET</STRONG>   Alternate character set

       X/Open Curses does not assign values to  these  symbols,  nor  does  it
       state  whether or not they are related to the similarly-named A_NORMAL,
       etc.:

       <STRONG>o</STRONG>   X/Open Curses specifies that each  pair  of  corresponding  <STRONG>A_</STRONG>  and
           <STRONG>WA_</STRONG>-using   functions   operates   on  the  same  current-highlight
           information.

       <STRONG>o</STRONG>   However, in some  implementations,  those  symbols  have  unrelated
           values.

           For example, the Solaris <EM>xpg4</EM> (X/Open) curses declares <STRONG>attr_t</STRONG> to be
           an unsigned short integer (16-bits), while  <STRONG>chtype</STRONG>  is  a  unsigned
           integer (32-bits).  The <STRONG>WA_</STRONG> symbols in this case are different from
           the <STRONG>A_</STRONG> symbols because they are used for a smaller  datatype  which
           does not represent <STRONG>A_CHARTEXT</STRONG> or <STRONG>A_COLOR</STRONG>.

           In this implementation (as in many others), the values happen to be
           the same because it simplifies copying information  between  <STRONG>chtype</STRONG>
           and <STRONG>cchar_t</STRONG> variables.

       <STRONG>o</STRONG>   Because  <EM>ncurses</EM>'s  <STRONG>attr_t</STRONG>  can  hold  a color pair (in the <STRONG>A_COLOR</STRONG>
           field), a call to <STRONG>wattr_on</STRONG>, <STRONG>wattr_off</STRONG>, or <STRONG>wattr_set</STRONG> may  alter  the
           window's  color.   If  the  color pair information in the attribute
           parameter is zero, no change is made to the window's color.

           This is consistent with SVr4 curses; X/Open Curses does not specify
           this.

       The  X/Open  Curses  extended  conformance  level  adds  new highlights
       <STRONG>A_HORIZONTAL</STRONG>,  <STRONG>A_LEFT</STRONG>,   <STRONG>A_LOW</STRONG>,   <STRONG>A_RIGHT</STRONG>,   <STRONG>A_TOP</STRONG>,   <STRONG>A_VERTICAL</STRONG>   (and
       corresponding  <STRONG>WA_</STRONG>  macros  for  each).   As  of  August 2013, no known
       terminal provides these highlights (i.e., via the <STRONG>sgr1</STRONG> capability).


</PRE><H2><a name="h2-HISTORY">HISTORY</a></H2><PRE>
       X/Open Curses is largely based  on  SVr4  curses,  adding  support  for
       "wide-characters"  (not  specific  to  Unicode).   Some  of  the X/Open
       differences from SVr4 curses address the way video  attributes  can  be
       applied  to wide-characters.  But aside from that, <STRONG>attrset</STRONG> and <STRONG>attr_set</STRONG>
       are similar.  SVr4 curses provided the basic features for  manipulating
       video  attributes.  However, earlier versions of curses provided a part
       of these features.

       As seen in 2.8BSD, curses assumed 7-bit characters,  using  the  eighth
       bit  of  a byte to represent the <EM>standout</EM> feature (often implemented as
       bold and/or reverse video).  The BSD curses library provided  functions
       <STRONG>standout</STRONG>  and  <STRONG>standend</STRONG> which were carried along into X/Open Curses due
       to their pervasive use in legacy applications.

       Some  terminals  in  the  1980s  could  support  a  variety  of   video
       attributes,  although  the  BSD  curses  library  could do nothing with
       those.  System V  (1983)  provided  an  improved  curses  library.   It
       defined  the <STRONG>A_</STRONG> symbols for use by applications to manipulate the other
       attributes.  There are few useful references for the chronology.

       Goodheart's book <EM>UNIX</EM> <EM>Curses</EM> <EM>Explained</EM> (1991)  describes  SVr3  (1987),
       commenting on several functions:

       <STRONG>o</STRONG>   the  <STRONG>attron</STRONG>,  <STRONG>attroff</STRONG>, <STRONG>attrset</STRONG> functions (and most of the functions
           found in SVr4 but not in BSD curses) were introduced by System V,

       <STRONG>o</STRONG>   the alternate character set feature with <STRONG>A_ALTCHARSET</STRONG> was added  in
           SVr2 and improved in SVr3 (by adding <STRONG>acs_map[]</STRONG>),

       <STRONG>o</STRONG>   <STRONG>start_color</STRONG>  and  related color-functions were introduced by System
           V.3.2,

       <STRONG>o</STRONG>   pads, soft-keys were added in SVr3, and

       Goodheart did not mention the background character or the <STRONG>cchar_t</STRONG> type.
       Those are respectively SVr4 and X/Open features.  He did mention the <STRONG>A_</STRONG>
       constants, but did not indicate their values.  Those were not the  same
       in different systems, even for those marked as System V.

       Different  Unix  systems  used  different  sizes  for the bit-fields in
       <STRONG>chtype</STRONG> for <EM>characters</EM> and <EM>colors</EM>, and took into account  the  different
       integer sizes (32-bit versus 64-bit).

       This  table  showing  the number of bits for <STRONG>A_COLOR</STRONG> and <STRONG>A_CHARTEXT</STRONG> was
       gleaned from the curses header files for various operating systems  and
       architectures.   The inferred architecture and notes reflect the format
       and size of the  defined  constants  as  well  as  clues  such  as  the
       alternate  character  set implementation.  A 32-bit library can be used
       on a 64-bit system, but not necessarily the reverse.

                                     <STRONG>Bits</STRONG>
       <STRONG>Year</STRONG>  <STRONG>System</STRONG>        <STRONG>Arch</STRONG>   <STRONG>Color</STRONG>  <STRONG>Char</STRONG>  <STRONG>Notes</STRONG>
       ------------------------------------------------------------------------
       1992  Solaris 5.2   32     6      17    SVr4 <EM>curses</EM>
       1992  HP-UX 9       32     no     8     SVr2 <EM>curses</EM>
       1992  AIX 3.2       32     no     23    SVr2 <EM>curses</EM>
       1994  OSF/1 r3      32     no     23    SVr2 <EM>curses</EM>
       1995  HP-UX 10.00   32     6      16    SVr3 <EM>curses</EM><STRONG>_</STRONG><EM>colr</EM>
       1995  HP-UX 10.00   32     6      8     SVr4, X/Open <EM>curses</EM>
       1995  Solaris 5.4   32/64  7      16    X/Open <EM>curses</EM>
       1996  AIX 4.2       32     7      16    X/Open <EM>curses</EM>
       1996  OSF/1 r4      32     6      16    X/Open <EM>curses</EM>
       1997  HP-UX 11.00   32     6      8     X/Open <EM>curses</EM>
       2000  U/Win         32/64  7/31   16    uses <EM>chtype</EM>

       Notes:

          Regarding HP-UX,

          <STRONG>o</STRONG>   HP-UX 10.20 (1996) added support for 64-bit  PA-RISC  processors
              in 1996.

          <STRONG>o</STRONG>   HP-UX  10.30 (1997) marked "curses_colr" obsolete.  That version
              of curses was dropped with HP-UX 11.30 in 2006.

          Regarding OSF/1 (and Tru64),

          <STRONG>o</STRONG>   These used 64-bit hardware.   Like  <EM>ncurses</EM>,  the  OSF/1  curses
              interface is not customized for 32-bit and 64-bit versions.

          <STRONG>o</STRONG>   Unlike  other  systems  which  evolved  from  AT&amp;T  code,  OSF/1
              provided a new implementation for X/Open curses.

          Regarding Solaris,

          <STRONG>o</STRONG>   The initial release of Solaris was in 1992.

          <STRONG>o</STRONG>   The <EM>xpg4</EM> (X/Open) curses was developed by MKS from 1990 to 1995.
              Sun's copyright began in 1996.

          <STRONG>o</STRONG>   Sun updated the X/Open curses interface after 64-bit support was
              introduced  in  1997,  but  did  not  modify  the  SVr4   curses
              interface.

          Regarding U/Win,

          <STRONG>o</STRONG>   Development  of  the  curses  library  began in 1991, stopped in
              2000.

          <STRONG>o</STRONG>   Color support was added in 1998.

          <STRONG>o</STRONG>   The library uses only <STRONG>chtype</STRONG> (no <STRONG>cchar_t</STRONG>).

       Once X/Open curses was adopted in the mid-1990s, the  constraint  of  a
       32-bit interface with many colors and wide-characters for <STRONG>chtype</STRONG> became
       a moot point.  The <STRONG>cchar_t</STRONG> structure (whose size and  members  are  not
       specified in X/Open Curses) could be extended as needed.

       Other interfaces are rarely used now:

       <STRONG>o</STRONG>   BSD  curses was improved slightly in 1993/1994 using Keith Bostic's
           modification to make the library 8-bit clean for <STRONG>nvi(1)</STRONG>.  He  moved
           <EM>standout</EM> attribute to a structure member.

           The  resulting  4.4BSD curses was replaced by <EM>ncurses</EM> over the next
           ten years.

       <STRONG>o</STRONG>   U/Win is rarely used now.


</PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
       <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>,     <STRONG><A HREF="curs_addch.3x.html">curs_addch(3x)</A></STRONG>,     <STRONG><A HREF="curs_addstr.3x.html">curs_addstr(3x)</A></STRONG>,     <STRONG><A HREF="curs_bkgd.3x.html">curs_bkgd(3x)</A></STRONG>,
       <STRONG><A HREF="curs_printw.3x.html">curs_printw(3x)</A></STRONG>, <STRONG><A HREF="curs_variables.3x.html">curs_variables(3x)</A></STRONG>



ncurses 6.5                       2024-04-27                     <STRONG><A HREF="curs_attr.3x.html">curs_attr(3x)</A></STRONG>
</PRE>
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<li><a href="#h2-NAME">NAME</a></li>
<li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
<li><a href="#h2-DESCRIPTION">DESCRIPTION</a>
<ul>
<li><a href="#h3-Window-Attributes">Window Attributes</a></li>
<li><a href="#h3-Legacy-Window-Attributes">Legacy Window Attributes</a></li>
<li><a href="#h3-Change-Character-Rendition">Change Character Rendition</a></li>
<li><a href="#h3-Change-Window-Color">Change Window Color</a></li>
<li><a href="#h3-Standout">Standout</a></li>
<li><a href="#h3-Video-Attributes">Video Attributes</a></li>
</ul>
</li>
<li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
<li><a href="#h2-NOTES">NOTES</a></li>
<li><a href="#h2-EXTENSIONS">EXTENSIONS</a></li>
<li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
<li><a href="#h2-HISTORY">HISTORY</a></li>
<li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
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